Method for operating a dishwasher, and dishwasher

Abstract

A method is provided for operating a dishwasher ( 1 ) in the form of a batch dishwasher, which has a treatment chamber ( 2 ) for accommodating washware to be cleaned. Provision is made, during an adsorption phase, for air to be conducted out of the treatment chamber ( 2 ) through a sorption unit ( 41 ), which contains a reversibly dehydratable dry material, in such a way that the dry material absorbs moisture from the air stream, wherein the air is then returned to the treatment chamber ( 2 ). Provision is further made, during a desorption phase, for the dry material of the sorption unit ( 41 ) to be heated in such a way that moisture is desorbed from the dry material as steam. During the desorption phase, the sorption unit ( 41 ) is subjected to forced ventilation only to such an extent that recondensation of desorbed steam in the sorption unit ( 41 ) itself is effectively prevented.

The invention claimed is: 
     
       1. A method for operating a dishwasher, which dishwasher has a treatment chamber for accommodating washware which is to be cleaned, wherein the method comprises the following method steps:
 i) during an adsorption phase, air is conducted out of the treatment chamber through a sorption unit, which contains a reversibly dehydratable dry material, in such a way that the dry material absorbs moisture from the air stream, wherein the air is then returned to the treatment chamber; and 
 ii) during a desorption phase, the dry material of the sorption unit is heated in such a way that moisture is desorbed from the dry material as steam, 
 wherein, during the desorption phase, the sorption unit is subjected to forced ventilation only to such an extent that recondensation of desorbed steam in the sorption unit itself is effectively prevented;
 wherein the desorption phase takes place within a time period of from 20 to 150 seconds in total; 
 wherein, for forced ventilation of the sorption unit, a fan is actuated in such a way that a volumetric flow rate of air which is forced through the dry material during the desorption phase is in a range of between 0.05 and 200 m 3 /h. 
 
 
     
     
       2. The method as claimed in  claim 1 , wherein a total of at least 10 litres of air is blown through the sorption unit during the desorption phase. 
     
     
       3. The method as claimed in  claim 1 , wherein, during the desorption phase, the sorption unit is subjected to forced ventilation in such a way that moisture which is desorbed from the dry material is discharged from the sorption unit as steam such that recondensation in the sorption unit is specifically effectively prevented. 
     
     
       4. The method as claimed in  claim 1 , wherein the air is continuously or intermittently blown through the sorption unit by a fan during the desorption phase. 
     
     
       5. The method as claimed in  claim 4 , wherein the temperature of the heated dry material is measured continuously or at predefined times or in the case of predefined events in the sorption unit during the desorption phase, and wherein the output capacity of the fan is controlled as a function of the measured temperature of the heated dry material in such a way that the dry material assumes a temperature of less than 300° C. 
     
     
       6. The method as claimed in  claim 4 , wherein the temperature of the air which is forced through the heated dry material is measured continuously or at predefined times or in the case of predefined events during the desorption phase, and wherein the output capacity of the fan is controlled as a function of the measured temperature of the air which is forced through the heated dry material in such a way that the air which is forced through the dry material assumes a temperature of less than 200° C. 
     
     
       7. The method as claimed in  claim 1 , wherein the temperature of the heated dry material is measured continuously or at predefined times or in the case of predefined events in the sorption unit during the desorption phase, and wherein the heating power of a heating unit which is arranged in the sorption unit is controlled as a function of the measured temperature of the heated dry material in such a way that the dry material assumes a temperature of less than 300° C. in the desorption phase. 
     
     
       8. The method as claimed in  claim 1 , wherein a total of 60 to 1000 kJ of thermal energy is supplied to the dry material during the desorption phase. 
     
     
       9. The method as claimed in  claim 1 , wherein the thermal energy is supplied by a heating power of a total of 3 to 7 kW during the desorption phase. 
     
     
       10. The method as claimed in  claim 1 , wherein the desorption phase is subdivided with respect to time into an initial first time period and a subsequent second time period, and wherein a fan is actuated in such a way that a quantity of air which is forced through the dry material during the first time period per unit time is lower than a quantity of air which is forced through the dry material during the subsequent second time period per unit time. 
     
     
       11. The method as claimed in  claim 1 , wherein the desorption phase is subdivided with respect to time into an initial heating phase, during which thermal energy is supplied to the dry material with the aid of a heating device at the same time as forced ventilation, and into a subsequent follow-up phase, during which only forced ventilation takes place and no thermal energy is supplied to the dry material by the heating device. 
     
     
       12. The method as claimed in  claim 1 , wherein the method also comprises the following program-controlled method steps which are to be executed one after the other:
 a) during a wash phase, wash liquid is sprayed into the treatment chamber from a tank with the aid of a wash pump by means of a wash line system through wash nozzles, wherein at least some of the sprayed wash liquid flows back from the treatment chamber into the tank due to the force of gravity; and 
 b) during a final-rinse phase, final-rinse fluid is conducted into the treatment chamber, 
 wherein method step ii) takes place at least partly during the wash phase and/or at least partly during the final-rinse phase. 
 
     
     
       13. The method as claimed in  claim 12 , wherein method step i) is carried out at the same time as or so as to overlap, with respect to time, with a drying phase which takes place following the final-rinse phase. 
     
     
       14. The method as claimed in  claim 12 , wherein method step a) lasts for a total of 5 seconds to 360 seconds. 
     
     
       15. A batch dishwasher comprising:
 a treatment chamber, into which washware can be manually inserted and from which washware can be manually removed; 
 a tank, into which liquid can flow off from the treatment chamber due to the force of gravity; 
 a wash system having a wash pump and a wash line system for conveying wash liquid out of the tank during a wash phase and for spraying the wash liquid through wash nozzles in the treatment chamber; 
 a fresh-water final-rinse system having at least one final-rinse pump and at least one final-rinse line system for conveying final-rinse liquid out of a fresh-water supply device during a fresh-water final-rinse phase and for spraying the final-rinse liquid through final-rinse nozzles in the treatment chamber; 
 a drying device for continuously drawing moisture, or drawing moisture as required, from drying air which circulates in the treatment chamber, wherein the drying device has at least one sorption unit, which contains a reversibly dehydratable dry material, and also at least one fan for forming an air circuit as required in such a way that air is conducted through the sorption unit and then supplied to the treatment chamber; and 
 a control device for carrying out the the following steps:
 (i) performing an adsorption phase in which air is conducted out of the treatment chamber through the sorption unit so that the dry material absorbs moisture from the air and the air is then returned to the chamber; and 
 (ii) performing a desorption phase in which the dry material of the sorption unit is heated such that moisture is desorbed from the dry material and returned to the treatment chamber; 
 wherein the control device is configured to control the sorption unit such that the desorption phase takes place within a time period of from 20 to 150 seconds in total and, for forced ventilation of the sorption unit, the fan is actuated in such a way that a volumetric flow rate of air which is forced through the dry material during the desorption phase is in a range of between 0.05 and 200 m 3 /h. 
 
 
     
     
       16. The dishwasher as claimed in  claim 15 , wherein the reversibly dehydratable dry material contains 0.3 to 3.0 kg of zeolite-containing material in the form of granules having a particle diameter of 0.5 to 10.0 mm. 
     
     
       17. The dishwasher as claimed in  claim 15 , wherein the drying device also has a heating unit for heating the reversibly dehydratable dry material as required, wherein the heating unit has a large number of heating elements which are preferably arranged at uniform distances within the reversibly dehydratable dry material. 
     
     
       18. The dishwasher as claimed in  claim 17 , wherein the drying device also has a heat exchanger unit which is connected to the sorption unit in such a way that, when an air circuit is formed, at least some of the air stream which is routed through the sorption unit also passes the heat exchanger unit. 
     
     
       19. A method for operating a dishwasher, which dishwasher has a treatment chamber for accommodating washware which is to be cleaned, wherein the method comprises the following method steps:
 i) during an adsorption phase, air is conducted out of the treatment chamber through a sorption unit, which contains a reversibly dehydratable dry material, in such a way that the dry material absorbs moisture from the air stream, wherein the air is then returned to the treatment chamber; and 
 ii) during a desorption phase, the dry material of the sorption unit is heated in such a way that moisture is desorbed from the dry material as steam,
 wherein, during the desorption phase, the sorption unit is subjected to forced ventilation to such an extent that recondensation of desorbed steam in the sorption unit itself is effectively prevented; 
 wherein operation of a fan during the desorption face, for the purpose of forced ventilation, is subdivided with respect to time into an initial first time period and a subsequent second time period, and wherein the fan is actuated in such a way that a quantity of air which is forced through the dry material during the first time period per unit time is lower than a quantity of air which is forced through the dry material during the subsequent second time period per unit time. 
 
 
     
     
       20. The method of  claim 19 ,
 wherein heating of the dry material during the desorption phase is subdivided with respect to time into an initial heating phase, during which thermal energy is supplied to the dry material with the aid of a heating device at the same time as forced ventilation, and into a subsequent follow-up phase, during which only forced ventilation takes place and no thermal energy is supplied to the dry material by the heating device.